influ_phyglm {sensiPhy}

Influential species detection - Phylogenetic Logistic Regression

Description

Performs leave-one-out deletion analysis for phylogenetic logistic regression, and detects influential species.

Usage

influ_phyglm(formula, data, phy, btol = 50, cutoff = 2, track = TRUE, ...)

Arguments

formula

The model formula

data

Data frame containing species traits with row names matching tips in phy.

phy

A phylogeny (class 'phylo') matching data.

btol

Bound on searching space. For details see phyloglm

cutoff

The cutoff value used to identify for influential species (see Details)

track

Print a report tracking function progress (default = TRUE)

...

Further arguments to be passed to phyloglm

Details

This function sequentially removes one species at a time, fits a phylogenetic logistic regression model using phyloglm, stores the results and detects influential species.

Currently only logistic regression using the "logistic_MPLE"-method from phyloglm is implemented.

influ_phyglm detects influential species based on the standardised difference in intercept and/or slope when removing a given species compared to the full model including all species. Species with a standardised difference above the value of cutoff are identified as influential. The default value for the cutoff is 2 standardised differences change.

Currently, this function can only implement simple logistic models (i.e. trait~ predictor). In the future we will implement more complex models.

Output can be visualised using sensi_plot.

Value

The function influ_phyglm returns a list with the following components:

cutoff: The value selected for cutoff

formula: The formula

full.model.estimates: Coefficients, aic and the optimised value of the phylogenetic parameter (i.e. alpha) for the full model without deleted species.

influential_species: List of influential species, both based on standardised difference in intercept and in the slope of the regression. Species are ordered from most influential to less influential and only include species with a standardised difference > cutoff.

sensi.estimates: A data frame with all simulation estimates. Each row represents a deleted clade. Columns report the calculated regression intercept (intercept), difference between simulation intercept and full model intercept (DIFintercept), the standardised difference (sDIFintercept), the percentage of change in intercept compared to the full model (intercept.perc) and intercept p-value (pval.intercept). All these parameters are also reported for the regression slope (DIFestimate etc.). Additionally, model aic value (AIC) and the optimised value (optpar) of the phylogenetic parameter (i.e. alpha) are reported.

data: Original full dataset.

errors: Species where deletion resulted in errors.

Author(s)

Gustavo Paterno & Gijsbert D.A. Werner

References

Paterno, G. B., Penone, C. Werner, G. D. A. sensiPhy: An r-package for sensitivity analysis in phylogenetic comparative methods. Methods in Ecology and Evolution 2018, 9(6):1461-1467.

Ho, L. S. T. and Ane, C. 2014. "A linear-time algorithm for Gaussian and non-Gaussian trait evolution models". Systematic Biology 63(3):397-408.

See Also

phyloglm, samp_phyglm, influ_phylm, sensi_plot

Examples

# Simulate Data:
set.seed(6987)
phy = rtree(100)
x = rTrait(n=1,phy=phy)
X = cbind(rep(1,100),x)
y = rbinTrait(n=1,phy=phy, beta=c(-1,0.5), alpha=.7 ,X=X)
dat = data.frame(y, x)
# Run sensitivity analysis:
influ <- influ_phyglm(y ~ x, data = dat, phy = phy) 
# To check summary results and most influential species:
summary(influ)
# Visual diagnostics for clade removal:
sensi_plot(influ)